Extract paths out of util (#13182)

This PR extracts the definition of the various Zed paths out of `util`
and into a new `paths` crate.

`util` is for generic utils, while these paths are Zed-specific. For
instance, `gpui` depends on `util`, and it shouldn't have knowledge of
these paths, since they are only used by Zed.

Release Notes:

- N/A

crates/assistant/src/assistant_panel.rs

@@ -40,6 +40,7 @@ use language::{
     LspAdapterDelegate, OffsetRangeExt as _, Point, ToOffset as _,
 };
 use multi_buffer::MultiBufferRow;
+use paths::CONTEXTS_DIR;
 use picker::{Picker, PickerDelegate};
 use project::{Project, ProjectLspAdapterDelegate, ProjectTransaction};
 use rustdoc::{CrateName, RustdocStore};
@@ -59,7 +60,7 @@ use ui::{
     prelude::*, ButtonLike, ContextMenu, Disclosure, ElevationIndex, KeyBinding, ListItem,
     ListItemSpacing, PopoverMenu, PopoverMenuHandle, Tab, TabBar, Tooltip,
 };
-use util::{paths::CONTEXTS_DIR, post_inc, ResultExt, TryFutureExt};
+use util::{post_inc, ResultExt, TryFutureExt};
 use uuid::Uuid;
 use workspace::NewFile;
 use workspace::{